The present invention relates to integrated optical waveguide devices and, in particular, polymer optical waveguide devices.
Planar optical waveguides can be formed with polymers, using a core polymer and a cladding polymer, with the core polymer having a refractive index slightly higher than that of the cladding polymer. Planar optical waveguides can be used to form various optical devices such as splitters, couplers, wavelength division multiplexers/demultiplexers, electro-optic modulators, thermo-optic switches, variable optical attenuators, optical waveguide amplifiers, etc. These devices operate in the near infrared region of the optical telecommunications wavelength window, and serve as building blocks of modern optical communications networks.
A general approach to making polymer optical waveguides is to dispose several undercladding polymer film layers on a substrate and then a polymer core film layer on top of the undercladding layer. The cladding and core layer formation processes, such as spincoating and vapor deposition, result in uniform cladding and core film layers with homogeneous composition over the entire substrate. The polymer core layer film subsequently undergoes lithography and etching processes from which a rectangular cross-section core is formed. Using a photomask, the subsequent lithography and etching processes result in channel waveguides that follow the photomask pattern. Using these processes, cores with a single material type are fabricated. An overcladding polymer film layer is then put on top of the waveguide core and the undercladding.
In some device applications, such as optical waveguide amplifiers, optical lossless splitters, electro-optic modulators, etc., it is of great benefit to have the ability to fabricate channel waveguide devices with multiple types of core materials, so that integrated devices with multiple functionalities can be formed on the same waveguide substrate. Due to the homogeneous nature of the core layer film, all of the core channels are presently composed of the same core material. However, in devices where multiple functionalities must be built on the same substrate, multiple types of core materials are required. It would be beneficial to provide a planar optical waveguide in which multiple types of cores are present.
Briefly, the present invention provides a planar optical waveguide comprising a substrate, a first cladding disposed on the substrate, and a first core disposed on a first portion of the first cladding. The first core is constructed from a first material. The optical waveguide also comprises a second core disposed on a second portion of the first cladding, with the second core being constructed from a second material and a second cladding disposed on the first core, the second core, and a remaining portion of the first cladding.
Additionally, the present invention provides a method of manufacturing a planar optical waveguide. The method comprises providing a substrate; disposing a first cladding layer over the substrate; disposing a first core material over the first cladding layer; forming a first core from the first core material, the first core being in a plane; disposing a second core material over the first cladding layer; forming a second core from the second core material, the second core being approximately in the plane of the first core; and disposing a top cladding layer over the first core, the second core, and an exposed portion of the first cladding layer.
Further, the present invention provides a method of manufacturing a planar optical waveguide. The method comprises providing a substrate; disposing a first cladding layer over the substrate; forming a first channel in the first cladding layer; disposing a first core material into the first channel; forming a second channel in the first cladding layer; disposing a second core material in the second channel; and disposing a second cladding layer on the first core material, the second core material, and at least a portion of the first cladding layer.